The present invention relates to an audio signal processing method and device. More specifically, the present invention relates to an audio signal processing method and device for performing binaural rendering on an audio signal.
3D audio commonly refers to a series of signal processing, transmission, encoding, and playback techniques for providing a sound which gives a sense of presence in a three-dimensional space by providing an additional axis corresponding to a height direction to a sound scene on a horizontal plane (2D) provided by conventional surround audio. In particular, 3D audio requires a rendering technique for forming a sound image at a virtual position where a speaker does not exist even if a larger number of speakers or a smaller number of speakers than that for a conventional technique are used.
3D audio is expected to become an audio solution to an ultra high definition TV (UHDTV), and is expected to be applied to various fields of theater sound, personal 3D TV, tablet, wireless communication terminal, and cloud game in addition to sound in a vehicle evolving into a high-quality infotainment space.
Meanwhile, a sound source provided to the 3D audio may include a channel-based signal and an object-based signal. Furthermore, the sound source may be a mixture type of the channel-based signal and the object-based signal, and, through this configuration, a new type of listening experience may be provided to a user.
Binaural rendering is performed to model such a 3D audio into signals to be delivered to both ears of a human being. A user may experience a sense of three-dimensionality from a binaural-rendered 2-channel audio output signal through a headphone or an earphone. A specific principle of the binaural rendering is described as follows. A human being listens to a sound through two ears, and recognizes the location and the direction of a sound source from the sound. Therefore, if a 3D audio can be modeled into audio signals to be delivered to two ears of a human being, the three-dimensionality of the 3D audio can be reproduced through a 2-channel audio output without a large number of speakers.
An audio signal processing device may simulate a sound source as a single dot in a 3D audio. In the case where the audio signal processing device simulates a sound source as a single dot, the audio signal processing device equally simulates audio signals output from sound sources which simulate objects having different sizes. Here, when the distance between a listener and the sound sources is short, the audio signal processing device may be unable to reproduce a difference between the audio signals delivered according to the sizes of the objects which output the audio signals.